Wastewater
Facts & Disposal Information
Understanding
Concrete Slurry & Environment Regulations
| Why
Do We Need Wastewater Control? |
With
increasing quality control standards and environmental
regulations, we are finding out that we cannot always do things
the same way as our grandfathers or even our fathers did things.
In an effort to meet increasing environmental regulations,
minimize waste and reduce operating costs, we are faced with the
task of developing efficient methods for recycling and/or
processing concrete wastewater.
Did
You Know? Only about
2.5% of the world's water is fresh water. The rest is salt
water. However, most of the fresh water is held in glaciers,
polar icecaps, locked in deep aquifers - thus not available for
human use. The result is that only about 0.25% of the
world's water, mostly in rivers, lakes and shallow aquifers, can
be used to meet human needs.
Impaired
Waterways Impact Us All 40%
of the waterways in the United States are still impaired (unable
to swim, fish, play or otherwise use the waterway) and 70% of
those are because of the discharging we've done with concrete
wastewater. As construction in the United States and
worldwide continues to boom, we are face with a pollution problem
of epidemic proportions.
What
is Concrete Slurry & Wastewater? Construction
sites have long been identified as a large contributor to urban
runoff pollution because of our negligence in not regularly
performing pollution prevention practices. Materials washed
into the storm drain have a direct impact on local waterways and
habitat living in that environment.
The
most common discharge into our storm drains from concrete
construction is the residue and contaminants from washing down
equipment such as concrete trucks, pumps, mixers, chutes, hand
tools and wheelbarrows.
Saws
and grinders use diamond blades to cut and grind concrete and
masonry products. With water being a necessary ingredient to
cool the diamond blades, the cutting and grinding process
generates a mixture of superfine material or sludge - also called
concrete slurry.
Concrete
Slurry & Wastewater is Caustic: Capable
of burning, corroding and destroying living tissues. Concrete
contaminated water typically has a high pH value, ranging between
11 and 12 on the pH scale. This type of high pH kills
fish and invertebrates (95% of all animal species) if allowed to
enter our environment and water bodies.
What
is pH? pH is a
measure of how acidic or alkaline a substance is. The pH
scale goes from 0 to 14, where 7 is neutral - which is water.
A pH less than 7 is acidic. A pH greater than 7 is basic.
The pH scale is also logarithmic, meaning a change in one pH unit
means a tenfold change in concentration - similar to the Richter
scale when measuring earthquakes. Mixing acids and basics
can cancel out or neutralize their extreme effects.
Why
Can't I Just Dilute the Run-Off to a Safer pH Level? Because
of the logarithmic scale of pH a huge volume of water is needed to
dilute the process water to a safe level - the dilution volumes
are huge. To dilute 1 gallon of concrete runoff, with a
pH reading of 12, to a safer pH of 7, would take approximately
100,000 gallons of water (or more). And if the correct
dilution rates are not achieved in the attempt to dilute the
contaminant, you would be increasing the size of the problem on a
massive scale . . . rather than fixing it.
Remember:
"Dilution isn't the solution"
High
pH Neutralization When
pH levels in storm water rise above 8.5 it is necessary to lower
the pH levels to the acceptable range of 6.5 to 8.5, this
process is called pH neutralization.
Effects
of High pH on Aquatic Life When
water comes into contact with cement, uncured concrete, concrete
dust, etc., it quickly produces a strong alkaline solution.
Its effects on fish may include: DEATH, damage to their
outer surfaces like gills, eyes, and skin, and an inability to
dispose of metabolic wastes. The safe
range for aquatic life is between 6.5 and 9.0 pH units. The
average pH of concrete wastewater is near 12 pH units.
If
even a small volume of concrete wastewater is allowed to
enter streams, lakes, wetlands or harbors through the storm water
system, it can cause immense damage to the environment. To
make things worse, with the pH scale being logarithmic the change
is ten-fold!
Effects
of High pH on Vegetation & Soil The
effects of high Ph on vegetation may inhibited growth, damage the
soil and plants, substantially alter the soil and plant chemical
composition even after the pollution source is gone.
High pH may also increase the toxicity of other substances causing
further problems. The safe range for
plant life is between 6.5 and 7.0 pH units. Once again:
the average pH of concrete wastewater is near 12 pH units.
Remember:
"Only rain goes down outside drains."
It's
the Law Construction
sites generally can contribute 10 to 20 times more sediment than
agricultural lands and 1,000 to 2,000 more times than forestlands.
During a short period of time, construction sites can contribute
more sediment than can be deposited over several decades, causing
physical and biological harm to our Nation's waters.
The
United States Environmental Protection Agency (EPA) and the
California Environmental Protection Agency have stepped up their
efforts in enforcing compliance to the US Clean Water Act and the
national Pollutant Discharge Elimination Systems.
Potential
discharges into the storm drain systems from concrete work has
become a priority of the federal and state EPA, water quality
control officials, regional and local inspectors as well as other
advocate and environmental groups.
The
illegal discharges into our waterways can bring fines of $10,000
per day plus $10 per gallon. And reach $30,000 per day if
the US EPA becomes involved.
Environmental
Regulations The EPA
monitors and limits the nature and magnitude of waste products a
site is allowed to discharge into the waters of the United States,
while local sanitary and sewer authorities set the limits for
total suspended solids, pH and chemical composition of allowable
concrete wastewater to be discharged into their local sanitary
sewer systems.
Pretreatment
for Concrete Wastewater Discharge into Local Sewers The
requirements for discharging concrete wastewater into local sewers
vary among authorities having jurisdiction. It has been
reported that the requirements for discharge into local sanitary
sewers are often less stringent than those required by the EPA and
often allow for higher pH limits.
Local
sanitary and sewer departments often charge additional fees for
discharging a high volume of concrete wastewater in addition to
the costs associated with handling and the safe disposal of
concrete sludge from settlement tanks.
Industrial
Contractors Supplies, Inc.
